Batboard

Our city radio system recently had a possible problem the other night and I wanted to get opinions, as I have practically zero knowledge of this site. Pardon the novel length....

System is SmartnetII+, 8 repeater channels. They said one of their guys had been called up to dispatch to check out a problem with console. I'm not sure what the deal was there but he had decided to go to the tower/site controller to snoop around. Apparently when he got there he discovered the fault light engaged on the CSC card. Not sure if he saw another problem or not, but in the process he decided to see if they were losing their control channel, or if it was switching (he said it switches from one of 4 repeaters every ?? hours). So, he started by turning Rep 1 off and then back on to see if Rep 2 would take over control ch. responsibility. It did, but Rep 1 stayed disabled (as indicated on the TIB card). He repeated the process (power cycling Rep 2, control jumps to 3, power cycling 3, control jumps to 4), and he got the same thing. So, naturally as this continues, they eventually have no control channel (as all are now disabled). They also said at one point when they power cycled on of the repeaters they think the entire control rack reset. They are also wondering why they can't disable the repeater(s) from the TIB card, rather than having to power cycle them.

So they called me this morning. I go out, they demonstrate the process they've been doing, and the system reacts as they previously described. 1st thing I notice is that on the system control cards, they have them in RUN position as they are doing their power cycling, rather than the SERVICE ENABLE position. The only other Smartnet/Smarttrunk/Smartwhatever system I've seen always stays in the SERVICE ENABLE position, so I turn the key switches to SERVICE ENABLE, and viola- they can now disable the repeaters via the TIB card swiches. So we go through the process of disabling each repeater, one at a time, to see if the next repeater will take over as the control channel. Lo and behold, it looks like it is working. So now they are wondering what's going on, I'm thinking maybe they were chasing their tails over a problem that wasn't there, but they want me to call Motorola to see what they say. My feeling is MOTO will not have much to say about it at all.

Question- on the only other site like this I have seen, the control channel does not switch from one repeater to another on a regular interval (although that seems like a good idea). Is this a normal feature of the SmartnetII+ system? Th city guy tells me it switches but I haven't witnessed it yet. How often does it switch?

Smartzone systems usually don't rotate the control channel, Smartnet systems (6809 controller) usually do unless system manager preference settings change that. The rotation is usually once a day at midnight.

If the tech disabled the repeaters by turning them off, the controller would see that as a no TSTAT fault and roll control to the next channel. That channel would be flagged to be re-tested by the controller, usually after 5 minutes. If he did that to all four control channels - boom - failsoft.

When you disable them from the TIB card - that is interpreted as a USER/MANAGER action and does not set the fault condition so that when you re-enable them they are immediately available for use - hence no failsoft.

It sounds like everything is working as it should.

Actually, when the tech saw a red light - which indicates that some sort of error ocurred - rather than turning things off - the proper action to take would be to hook a diagnostic terminal [e.g. laptop running procomm] up to the CSC. There will be a dump of diagnostic messages which you can then interpret using the service manual to determine the cause of the issue.

XMO's comments sound to be accurate to my experience.

As for the Run/Service switches, They should be left in the run position except when doing on-site service.

When testing, turn them to the service position. At that time you should be able to disable/enable from the TIB (or RIB I believe). When you re-enable from the TIB the staion will imediatly be tested and put back into service.

Just to re-inforce it and make it a three-some I will concur that my experience has been that if you are disabling channels, when you re-enable the channel, make sure that the key is in "Service Enable" or the channel will not re-enable properly.

Thanks for the replies folks.

my experience has been that if you are disabling channels, when you re-enable the channel, make sure that the key is in "Service Enable" or the channel will not re-enable properly.

Mine as well, as the only other system I've actually done anything with has always been left in service mode. I've never seen the way a system acts when in run mode.

the proper action to take would be to hook a diagnostic terminal [e.g. laptop running procomm] up to the CSC.

That was my thought if it happens again. I've got my service monitor on at my house, watching the control channel now. We'll see what happens at midnight.

Just to re-iterate what others have said above, the keys do have to be in the 'service enable' position in order to use the TIB & RIB disable buttons. It won't affect normal system operation to leave them in the 'service enable' position, but it would allow an unauthorized person to disable/enable repeaters. It should be left in the 'run' position, and the key(s) really shouldn't be left onsite, if security is a concern at all.

Todd

My two bits worth:
When ever you look at a controller always measure the power supply voltages. Also measure noise or ripple, especially on the old 21 channel controllers.

On automatic control channel assignment we presume that the control channel will rotate every midnight, providing the controller code plug CSCU48 is so programmed. Consult the "birth certificate" which is hopefully with the controller.
Note AMSS systems only have one control channel.

The channel will change unless:
1) channel is "Protected" by the Syst Manager.
2)Channel is "protected" by interconnect or other option.
For example:
A 5 channel system with interconnect installed per instructions, channels 1,2,3, channel 4 will be control unless it is disabled
This is why I use channels 3,4,5 for interconnect, then control will cycle between channels 1 and 2.

On 3 channel controllers, channel 3 can never be assigned control, because it is preempted by the base ID, which is on the lowest channel.
It is possible to assign ch 3 as "VC" , although it can never be control.

When installing controller cards it is often necessary to support the card cage mother board. Tight connectors can cause the mother board to bow out when the front panel of the board touches the rail. This causes no operation, or worse yet a later failure because the edge connector was not fully seated.

10-4 on the power supply advice Bernie. On the older (type I- Smart trunk???) systems we maintain, 5V power supply issues have been pretty much the only issues we've had.

My two bits worth:
The day after my last post, I had a project:
PMI check of a 6 channel trunking system at an oil refinery.
This is a "Smartworks", a 7 channel 6809 controller.
The power supply is in a drawer in the bottom of the case. The 28 channel controllers are very similar.
I measured the DC voltages, as well as ripple and hum. I use the AC scale of my meter. The 5 V supply had 500mv hum.
Two power supplies with a diode combiner.
Each voltage has an indicator.
When I turned the right supply off the controller crashed.
The left supply failed.
Fortunately there were no symptoms yet.

The power supplies are very reliable, however Electrolytic Capacitors have a finite life span. 16 years in this case.

A failure in a 5 V supply usuially results in a dead controller, or multiple resets.
Plus, and minus 12V supplies run the op amps in the IRB as well as the interconnect chassis.
Noise on a 12V supply can cause difficulty in accessing the system.
Hum on interconnect.

The 12V power supply for the 21 channel controller has had problems with filter caps with clear jackets. The blue ones seem OK.